/* 基础样式 */
.nav-menu {
    list-style: none;
    padding: 0;
  }
  
  .nav-item {
    margin-bottom: 5px;
  }
  
  .nav-link {
    display: block;
    padding: 10px;
    text-decoration: none;
    color: #333;
    background-color: #f8f9fa;
    border-radius: 4px;
    transition: all .2s ease-in-out;
  }
  
  .nav-link.has-submenu {
    display: flex;
    justify-content: space-between;
    align-items: center;
  }
  
  .submenu-toggle-icon {
    transform: rotate(-90deg);
    transition: transform .2s ease-in-out;
  }
  
  .submenu-toggle-icon.open {
    transform: rotate(0deg);
  }
  
  /* 缩进子菜单项 */
  .sub-menu {
    list-style: none;
    padding-left: 20px; /* 添加缩进 */
    max-height: 0;
    overflow: hidden;
    transition: max-height .3s ease-out;
  }
  
  .sub-menu.open {
    max-height: 500px; /* 设置一个较大的值 */
    transition: max-height .3s ease-in;
  }
  
  .active .nav-link {
    background-color: #007bff;
    color: #fff;
  }